Device for cutting screw-threads.



fr onirica.

CLEMENS WINCKELIVIANN,y OF BERLIN, GERMANY.

DEVICE FOR CUTTING SCREW-THREADS.

' Specification of Letters Patent.

Patented July 3o,190'7.

Application filed July 26, V1901. 'Serial No. 69,773.

To all whom it may concern:

:Be it known that l, 4Gianni-ms WINCKELMANN, a subject oi the German Emperor, oi No. 9i and 92 Alt- Moabiti, Berlin, in theEmpire oi Germany, manufacturer, have invented a certain new and useiul ImprovedDevicc l or Cutting ScreW-flhreads, oi which the following is a clear, full, and exactdescription.

This invention relates to improvements in screw cutting machines oi that Class, in which two 0r more tools are employed lor cutting the same blank It is especially designed lor cutting wood screws to be made with comparatively long threads, and is adapted tor ilse in connection with thegeneral type oi machine illustrated and described in United States Letters Patthe screws to be made in a quicker manner; the independent adjustment oi' that. tool which is cutting the portion close to the point ol the screw allows oi' the properloi-mation or threadingr oi' the screw point.

Referring to the accompanying drawings, Figure l is a plan assuming the tool holders d c to be located in the horizontal plane ol' the yoke r; Fig. lu is a diagrammatical view oi the arrangement ot' the tool holders and the yoke with tht` cam wheel i'or determining the position ol the tools. Fig. l" is a rear view oi the yoke and toolv holders, showing also the blank hel d in the lathe chuck, the line G-H of this iig. indicating the section-plane for Fig. 11. Fig. 2 is a section on line A-B of Fig. l; Fig'. 3 is a section Von line E-F oi Fig, l.

The arrangement shown in the drawings indicates how the invention can be carried out with two tools.

r1 and b are the two tools operating on the same side against the screw blank held in a lathe chuck 'w as shown in FigA l." (rear View). The blank is supported by a semi-hollowtai abutment (not shown in the draw ing) iu a known manner. The distance between the two tools isso regulated that it corresponds to onehali ol' the length oi the screw thread to be made. When the tool u is cutting the inner part oi' the thread (up to the middle) the tool l: cuts the thread on the other part up to the screw point. The adjustment must be suchthat the thread-cut made by the one tool runs into the other. 1t is obvious that if there were three tools, the distance would be redueed to one third. This indicates the length over which the stroke must extend, which is im* parted to the tool holders. l

e and n' are the tool holders ior the tools a and b respectively. The tool holder c is adjustably attached a sleeve llooselymounted on the shaitfis a connecting bracket lc, and the holder (Z can slide on the same and be secured by a screw m in its adjusted position. By this connection, any rocking movement oi the sleeve l is transmitted to the tool holder The sha-it f carrying the sleeve Z, which `has no independent longitudinal play thereon, is slidably mounted in bearings oi the machine trame and is moved longitudinally by means of a revolving cam 'a attached to the shait n, whicli derives its turning motion from the driving mechanism ofthe machine. The end oi the shaitf is hollow and a pin j, preferably made oi hardened steel, is inserted therein. When the shai t n rotates, this pinf/ is acted on by the eam n., thus producing the'longitudinal movement oi the shaltfand sleeve l together with' the tool holders c d in the direction of the arrow y (Fig. l). By means oi a spring t, these c0nnected parts are retracted in the opposite direction, so that the return stroke takes place according as the cam n allows of such movement. pitch oi' the stroke ot the cam' need not be apprcciably greater than one halt' oi the length oi the screw thread to be made on the blank, thus voiding the diiiiculty of constructing comparatively large cams having pitches corresponding to the feed along the whole length of the screw thread.

Each of the tools is moved laterally against the screw blank by independent rocking motion transmitted by the shait f and sleeve Z respectively. For this-purpose, the shaft f is provided with an abuttin'g arm o and the slecve Z With an abutting arm p, both arms being in juxtaposition and located with their ends in the path of a rail q. The latter is iixed at the rear side of a shifting 'yoke r, which is pivotally suspended on the shaft f as shown in Fig. l and is adapted to be lowered gradually so as to depress the abutting arms sliding on the rail q to the extent necessary ior allowing the tools' to cut into the blank. Th e well kno'wn means for effecting this shifting action may consist oi an arm il (Fig. 1") attached to the yoke rand a cam wheel 'u provided with cam projections e', of, fr, 1:", e5, c and 'o7 which succcssively act upon the arm it when it is turned in the direction oi the arrow by a suitable ratchet mechanism. According as the .higher steps'oi the cam wheel 11 act against tlnI arm 'Ji the yoke r will be more depressed and the tools will eut deeper into the blank. This shitting mechanism is well known in screw cutting machines and iorms no part ol' the invention. lt will be understood that alter each feed strokehas ta ken place ai d the iront tool b has arrived at the end oi' the blank, both 1t is obvious that thc4 tool holders are tilted back and then the return stroke takes place until the tools assume the starting'position. The heads of the abutting arms o p slide, duringfthis reciprocatory movement, on the rail q as shown in Fig. 1b. The rail q is provided with an incline s at the one end and While the abutting ami o does notire'ach up to this incline s when passing along the rail, the other abutting arm p rides on the incline s at the end of the stroke. Thus the sleeve land tool holder d are tilted against the axis of the blank, so that the tool b produces the threadingand cutting of the screvv point (as indicated in dotted lines in Fig. 1b) before 'each feed stroke is completed.

It is obvious to anyone versed in the art that before the screw cutting is commenced, the blank, previously formed with a head, is grasped by the chuck such'as w (Fig. 1b) and presented to the tools While it is supperted from the rear by the counter-bearing. Then by the reciprocatory movement of the Qools, the thread is cut in the described manner under the condition that .the tools in the starting position are every time advanced to cut deeper than in the preceding,r stroke.

, Since the blank in the device according to the inventionv is engaged by the tools simultaneously at twov points considerably apart from each other, the blank is p1 operly held against its counter-bearing which is semihollowed as above-stated. The advantage thus at- -tained is that the accidental displacement from the central position and deformation oi the screw are avoided.- A further advantage is that by the limitation ol' the stroke to a part o1' the entire length of thc thread i. c. one haii for the example shown, the reeiprocatory movement can take place more rapidly, so that the iinishing of each screw is el'lected in a shorter space of timehthan when adopting the usual arrangement in which the tool or tools are cach time carried along the entire length ol' the thread.

The fact that the tool holders can be adjustably lix'ed independently eimbles their adaptation to dii'l'crent sizes ol' screws. lhe adjusting device comprising the externally threaded hub y, shown in Figs. l and 2 as connected with the tool holder rl., serves to increase and decrease the distance between tlul toolholders.

The connecting bracket lc is provided with a slide way (Figs. l and lf) for the purpose of sliding 'engagement with the tool holderd which is thus capable of axial sliding movenrent if the screw m is loosened. The adjustment is effected by screwing the hub y more or less through the screw-threaded lcore o the tool holdr, whereby the latter is shifted into the desired position; then it is fixed in this position by tightening the scrcwm.

It will be seen from the drawings (Fig. l), that the abutting 'arms o and p are also adjustably fixed on the shaft f and the sleeve lrespectively, by means of clamping` screws, so -as to enable the operator'to regulate the tilting movement .ofi the tool holders.

Having now particularly described and ascertained the nature of the said invention, I declare that what, I claim and wish to secure by Letters Patent istl. In a device for cutting.: screw threads. a shaft, a cutting tool holder adjustably secured thereto, a sleeve slidably and rotatably mounted on said shaft. a cutting,r tool' holder adjustabiy secured to said `sleeve and rotatable about said shaft, cutting tools secured to cach of said holders. and means for operating,r said holders and tools independently of euch other, substantially as shown and described. "Y

2. ln a device for cutting screw threads, n shaft, n. tool holder :uijnstably secured thereto, a sleeve siidably and rotatably mounted on said shaft, a tool holder secured to the said sleeve and rotatable about said shaft, cutting tools secured in each'of said holders, an abutthurr arm adjustz'ibiy secured to said sleeve and another abutting arm adjuslably secured to said shalt, a yoke. a rail secured to said yoke and upon which said abutting arms` slide u cam mechanism producing reciln'ocatory'movement for said shal'l'. means for maintaining the contact of said shaft with said cam mechanism and means for operating: said rum mechanism, substantially as shown and described.

1%. in a device for cuti'lnf.: screw threads, a shaft, a sleeve loosely mounted on said shaft, n tool holder adjustabiy secured to said sleeve. :md provided with a screw threaded core an externally screw threaded hub mounted en said shaft, and engaging.; said screw threaded core, .ubsl:|ntinlly :is shown and described.

ln witness whereof i have hereunto set my hund in presence ot' two witnesses.

CLEMHNS Wl Nt KICLMANN.

\\'itnesses wonnen/iu liAur'r, Iii-:Nur ilAsrlcu. 

